Hitherto, as a chuck structure of this type, there has been known an outer diameter collet chuck which includes a collet having a plurality of gripping claws arranged along a circumferential direction of the collet (Patent Literature 1). That is, in the outer diameter collet chuck, an outer surface on a distal end side of each of the gripping claws is formed into a tapered surface tapered from a distal end side of each of the gripping claws to a proximal end side thereof, and a radially inner surface of a cylindrical part, which is arranged on an outer peripheral side of each of the gripping claws, is formed into a tapered surface tapered from a distal end side of the cylindrical part to a proximal end side thereof. Accordingly, the gripping claws are tightened and loosened through reciprocation in an axial direction. Thus, the gripping claws can chuck a workpiece from a radially outer side of the workpiece.
Further, hitherto, there has been known a chuck device using a pair of leaf spring members, though the chuck device is not configured to chuck an annular workpiece (Patent Literature 2). That is, the pair of leaf spring members clamps the workpiece.